<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>输出信息</title>
    <script>
        //第五题
        var str = '我是"JavaScript"，JavaScript是一门弱类型语言';
        document.write(str + '<br>');
        // 第六题
        document.write(str.indexOf("Java") + '<br>');
        document.write(str.slice(15, 25) + '<br>');
        document.write(str.substr(28) + '<br>');
        document.write(str.replace('JavaScript"', "张三") + '<br>');
        document.write(str.substring(0, 16) + str.substring(16, 25).toUpperCase() + str.substring(26, 35));
    </script>

</head>
<body>
    
</body>
</html>